Earth and Planetary Sciences ETDs

Publication Date

12-1974

Abstract

The northern Sierra Cuchillo, Socorro and Sierra Counties, New Mexico is approximately 32 miles northwest of Truth or Consequences, New Mexico. The Sierra Cuchillo is a narrow fault-block range in the Basin-Range province and is a structurally high element west of the Rio Grande trough. It is bordered on the west by the Winston graben and the Black Range and on the east by Monticello graben and the San Mateo Mountains.

Permian rocks consist of the Yeso and San Andres Formation, with an aggregate thickness of 2100 ft (640 m). Upper Cretaceous rocks, 40 ft (10 m) thick, consist of interbedded shale, conglomerate, and sandstone. The Pre-Tertiary rocks are in fault contact with the Tertiary volcanic rocks.

The tertiary volcanic rocks (Oligocene) in the area consist of andesite-latite of Montoya Butte, made up of thick tuff-breccia and lava of andesitic of latitic composition, 2000 ft (610 m); Vicks Peak Rhyolite ash-flow tuff, 7-1200 ft (2-370 m); latite flow of Grapevine Canyon, 20-7—ft (6-210 M); quartz latite porphyry of Whitewater Canyon, 1500 ft (460 m); flow-banded rhyolite of Alamosa Creek, 700 ft (10 m); rhyolite tuff of Shipman Canyon, 600 ft (180 m); and rhyolite tuff of Spring Canyon, 250 ft (75 m). The andesite-latite of Montoya Butte is intruded by dikes of latite, quartz latite, andesite, and porphyritic rhyolite.

Clastic sedimentary rocks of the Santa Fe Group (Miocenc-Pliocene) occur along the west, north, and east edge of the map-area and are probably equivalent to the Winston beds. The Santa Fe Group consists of poorly sorted siltstone, sandstone and conglomerate, derived mainly from local volcanic rocks. An olivine basalt flow, 10 ft (3 m) thick, is interbedded with the group.

Beryllium mineralization is present near the west end of Monticello Canyon, where the ore mineral is bertrandite. Kaolinzation, alunitization, montmorillonitization and silicification alter volcanic rocks along faults near the area of beryllium mineralization. Secondary calcite is common in fault breccias.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Wolfgang Eugene Elston

Second Committee Member

Lee A. Woodward

Third Committee Member

J. Paul Fitzsimmons

Language

English

Document Type

Thesis

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